1. Field of the Invention
The present invention relates to a friction clutch of a motor vehicle and more particularly, it relates to an articulation head for a clutch-release rocker arm of a friction clutch of a motor vehicle.
2. Description of the Related Art
A clutch-release rocker arm with an articulation head is known, for example, from EP 0,253,118 A1. One end of the clutch-release rocker arm described in this document is mounted on an actuating bolt, while the other end is mounted on the articulation head. The actuating element has a hydraulic cylinder for axial displacement of the actuating bolt and therefore for displacement of a clutch-release bearing. The clutch release bearing is arranged in a central area of the clutch-release rocker arm of the friction clutch. The clutch-release rocker arm can therefore be pivoted very easily about the articulation head.
A drawback of the known articulation head is that it quickly becomes worn. For example, material abraded from the friction clutch can penetrate between the ball head and the ball socket and damage these components at this location. Moreover, this wear leads to a high level of noise emissions. In the known articulation head, lubrication of the articulation head with grease does not permanently reduce the wear, since the abraded material from the friction clutch can become permanently mixed with the grease and may therefore still cause wear to the articulation head.
It would be conceivable to seal the articulation head using a sealing lip which bears against the ball head. However, this design also fails to limit the wear to the articulation head in the long term, since the sealing lip itself may become worn by the abraded material. Furthermore, the sealing lip results in a considerable limitation to the pivoting angle of the ball head in the ball socket. In addition, since the sealing lip has to bear against that side of the ball head which is remote from the ball socket, it is extremely complex to install.